The present invention relates to an intramedullary bone fixation device and to a method of fixing an intramedullary device to a bone. The apparatus and method of the present invention are especially suitable for stabilising bone fractures and for fixing prostheses, such as artificial hips, knees or other joints, into bones.
The present invention also relates to an apparatus for fixing to a structure, beam, member, wall, or the like. The apparatus may be adapted to have other connecting apparatus, such as bolts, screws, nails, hooks or the like affixed thereto, or it may be adapted to join elements, such as bricks, beams, or the like, together.
Fixation and stabilisation of fractures can be difficult, especially in long bones. Two techniques are normally used. The first technique involves placing a plate on one side of the bone and screwing the plate to the bone on either side of the fracture with a plurality of screws. This technique suffers from the disadvantage that forces are applied to the bone via the screws from one side of the bone only, which can cause uneven loading on the bone.
The second technique for fixation and stabilisation of fractures involves inserting an intramedullary pin into the medullary canal of the bone. Fixation pins may or may not be used. If fixation pins are not used, the bone at either side of the fracture may rotate around the intramedullary pin which leads to misalignment of the bone. If fixation pins are used, it is necessary to drill holes through the bone on either side of the fracture and insert fixation pins through the holes in the bone and through holes formed in the intramedullary pin. It is often difficult to align the holes in the bone with those in the intramedullary pin, thereby complicating the operative procedure and potentially causing an increase in post-operative recovery time for the patient.
Fixation of prosthesis, such as artificial hips and artificial knees, also faces similar difficulties. For example, fitting an artificial hip to a patient typically involves preparing the upper part of the femur and inserting a stem portion of the hip prosthesis into the medullary canal of the femur. The stem is fixed to the femur by bone cement or by inserting external pins through holes drilled through the femur and into and through holes in the stem portion of the artificial hip. The difficulties with using external pins have been discussed above. In cases where bone cement is used, misalignment and shifting of the prostheses can occur if the cement does not adequately adhere to the bone.
It is an object of the present invention to provide a device and a method that overcomes or at least ameliorates one or more of the above-mentioned disadvantages of the prior art.
In a first aspect, the present invention provides an intramedullary bone fixation device comprising a hollow elongate member having at least one opening in a side wall thereof, the hollow elongate member being adapted for insertion into a medullary canal of a bone, and an inner member sized to be slidably receivable within the hollow elongate member, the inner member carrying at least one pin, the inner member having one or more grooves in an outer surface thereof, said at least one pin being positioned in the one or more grooves when the at least one pin is in a retracted position, at least one pin being pivotally connected at one end thereof to the inner member, the at least one pin being movable from a retracted position to an extended position in which the at least one pin extends through respective ones of the at least one opening in the hollow elongate member, and wherein the at least one pin as moved to the extended position by placing free ends of the at least one pin into alignment with the one or more openings and rotating the inner member to thereby extend the pins through the one or more openings.
In another aspect, the present invention provides an intramedullary bone fixation device comprising a hollow elongate member having at least one opening in a side wall thereof, the hollow elongate member being adapted for insertion into a medullary canal of a bone, and an inner member sized to be slidably receivable within the hollow elongate member, the inner member carrying at least one pin, the at least one pin being movable from a retracted position to an extended position in which the at least one pin extends through respective ones of the at least one opening in the hollow elongate member, wherein the at least one pin has an enlargement at one end thereof and the enlargement rests in a respective hole or recess formed in the inner member and the at least one pin extends along respective grooves formed in the inner member when in the retracted position, wherein the one or more pins are retained in place by an inner wall of the hollow elongate member and the one or more pins are extended by aligning free ends thereof with the at least one opening in the hollow elongate member and rotating the inner member.
The distal end of the hollow elongate member may have a point or a closed end at the distal end thereof to facilitate insertion of the hollow elongate member into the medullary canal. The distal end of the hollow elongate member is preferably provided with a conical point, which may be formed integrally with the hollow elongate member or provided as a separate part that is subsequently affixed to the hollow elongate member.
The inner member is preferably a solid member but it may also comprise a hollow member. The inner member is preferably sized to fit snugly but not too tightly into the hollow elongate member to thereby allow easy movement of the inner member within the hollow elongate member whilst avoiding slack or xe2x80x9cloosenessxe2x80x9d between the inner member and the hollow elongate member. Preferably, both the inner member and the hollow elongate member are cylindrical for a major portion of their length.
The inner member carried the at least one pin. It is preferred that the inner member carries a plurality of pins. The hollow elongate member should have at least the same number of openings in its side wall as pins on the inner member. Alternatively, the opening(s) may be shaped such that two or more pins may extend therethrough. For example, the hollow elongate member may be provided with a slot through which two or more pins may project
The one or more pins are the means by which the device of the present invention is held in position with respect to the bone. In use of the device of the present invention, the device is inserted into the intramedullary canal of the bone. Once in the desired position, the pins are moved from the retracted position to the extended position. In the extended position, the or each pin extends through a hole in the side wall of the hollow elongate member and into the bone, thereby fixing the relative position of the device and the bone. The device is simple to use because it does not require holes to be drilled through the bone to cater for external fixing pins. It also securely holds the bone in position relative to the device.
In preferred embodiments of the present invention, a plurality of pins are carried by the inner member in order to firmly fix or connect the device to the bone. For convenience of description, the invention will hereinafter be described with reference to a plurality of pins. However, it will be understood that the objects of the present invention could be met with a single pin and that such an embodiment falls within the scope of the present invention.
In the retracted position, the pins preferably do not extend beyond the outer diameter or perimeter of the hollow elongate member. In the extended position, the pins extend through the holes in the side wall of the hollow elongate member and into the bone.
In the preferred embodiment of the present invention, the inner member is provided with one or more grooves in an outer surface thereof. Such grooves are suitably generally transverse grooves. The pins are placed in the grooves and pivotally connected at or near one end to the inner member. The other end of each pin may extend slightly beyond the surface of the inner member. In order to move the pins to the extended position, the inner member may be rotated or turned when the free ends of the pins are in alignment with the holes in the side wall of the hollow elongate member. The free ends of the pins will extend through the holes. As rotation of the inner member continues, the distance between the pivotally mounted ends of the pins and the holes in the hollow elongate member decreases and this causes the pins to move outwardly through the holes until they are fully extended.
In order to enable the inner member to be rotated with the force required to extend the pins into the bone, the proximal end of the inner member may be provided with an engaging surface for engaging with a handle or a torque applying means. To avoid or minimise rotation of the hollow elongate member may also be provided with a holding surface for holding the hollow elongate member in position. The holding surface may be a square, rectangular, hexagonal or other polygonal surface on the proximal end of the hollow elongate member. Alternatively, the hollow elongate member may be provided with a keyway to engage with a suitable tool to hold the hollow elongate member in position.
The hollow elongate member and the inner member may be fixed length members or they may be of variable or adjustable length. Variable or adjustable length members are especially useful in cases where the device is used for fixating fractures and it is desirable to adjust the length of the device during healing of the fracture.
The present invention also encompasses a method of fixing an intramedullary device to a bone comprising providing an intramedullary bone fixation device comprising a hollow elongate member having at least one opening in a side wall thereof, the hollow elongate member being adapted for insertion into a medullary canal of a bone, and an inner member sized to be slidably receivable within the hollow elongate member, the inner member carrying at least one pin, the at least one pin being movable from a retracted position to an extended position in which the at least one pin extends through respective one or ones of the at least one opening in the hollow elongate member, inserting the intramedullary device into the medullary canal of the bone, and extending the at least one pin from the retracted position to the extended position in which the pins extend through respective one or ones of the at least one opening in the side wall of the hollow elongate member and into the bone to thereby fix the relative position of the device and the bone.
Preferably, the device is provided with a plurality of pins.
In one embodiment, the step of inserting the device into the medullary canal of the bone comprises inserting the hollow elongate member into the medullary canal and subsequently inserting the inner member into the hollow elongate member. Alternatively, this step may comprise inserting the inner member into the hollow elongate member and subsequently inserting the hollow elongate member into the medullary canal. As a further alternative, this step may comprise partly inserting the inner member into the hollow elongate member, inserting the hollow elongate member into the medullary canal and then fully inserting the inner member into the hollow elongate member.
The step of moving the pins from the retracted position to the extended position may comprise rotating the inner member to thereby move the pins so that they extend through the at least one hole in the side wall of the hollow elongate member. The hollow elongate member is preferably held in position whilst the inner member is rotated.
Preferably, pins extend into the bone on either side of a fracture once the device has been fitted, if the device is being used for stabilising or fixing a fracture.
The present invention also provides an apparatus that can be used in the building industry or other industries as a connector or connections or for joining two or more elements together or for fixing to a structure, beam, member, wall or the like.
In another aspect, the present invention provides an apparatus for fixing to a structure, beam, member or the like comprising a hollow elongate member having at least one opening in a side wall thereof, the hollow elongate member being adapted for insertion into a hole in a structure, beam, member or the like, and an inner member that is insertable into the hollow elongate member, the inner member carrying at least one pin, the inner member having one or more grooves in an outer surface thereof, said at least one pin being positioned in the one or more grooves when the at least one pin is in a retracted position, the at least one pin being pivotally connected at one end thereof to the inner member, the at least one pin being movable from a retracted position to an extended position in which the at least one pin extends through respective ones of the at least one opening in the hollow elongate member, and wherein the at least one pin as moved to the extended position by placing free ends of the at least one pin into alignment with the one or more openings and rotating the inner member to thereby extend the pins through the one or more openings.
In yet a further aspect, the present invention provides an apparatus for fixing to a structure, beam, member or the like comprising a hollow elongate member having at least one opening in a side wall thereof, the hollow elongate member being adapted for insertion into a hole in the structure, beam, member or the like, and an inner member in the hollow elongate member, the inner member carrying at least one pin, the at least one pin being movable from a retracted position to an extended position in which the at least one pin extends through respective ones of the at least one opening in the hollow elongate member, wherein the at least one pin has an enlargement at one end thereof and the enlargement rests in a respective hole or recess formed in the inner member and the at least one pin extends along respective grooves formed in the inner member when in the retracted position, wherein the one or more pins are retained in placed by an inner wall of the hollow elongate member and the one or more pins are extended by aligning free ends thereof with the at least one opening in the hollow elongate member and rotating the inner member.
The distal end of the hollow elongate member, being the end that is inserted into the hole in the structure, member, beam, wall or the like, preferably has a closed end. This will avoid the hollow elongate member possibly filling with debris when inserted into the hole in the structure or the like (hereinafter, the term xe2x80x9cstructure or the likexe2x80x9d will be used to refer to the xe2x80x9cstructure, beam, member, wall or the likexe2x80x9d for the sake of brevity). A closed end on the hollow elongate member will also act as a stop member for the inner member and ensure that the inner member is inserted to the to the correct depth into the hollow elongate member. The distal end of the hollow elongate member may be provided with a pointed or generally conical end to assist with insertion into the hole of the structure or the like.
The inner member is preferably a solid member but it may also comprise a hollow member. The inner member is preferably sized to fit snugly but not too tightly into the hollow elongate member whilst avoiding slack or xe2x80x9cloosenessxe2x80x9d between the inner member and the hollow elongate member. Preferably, both the inner member and the hollow elongate member are cylindrical for a major portion of their length.
The inner member carried the at least one pin. It is preferred that the inner member carries a plurality of pins. The hollow elongate member should have at least the same number of openings in its side wall as pins on the inner member. Alternatively, the opening(s) may be shaped such that two or more pins may extend therethrough. For example, the hollow elongate member may be provided with a slot through which two or more pins may project.
The one or more pins are the means by which the device of the present invention is connected to the structure or the like. In use, the apparatus is inserted into a hole in the structure or the like. The hole in the structure or the like may be made by drilling or by forming during manufacture or construction of the structure or the like. When the apparatus has been inserted to the desired depth, the pins are moved from the retracted position to the extended position in which the pins extend into the material of the structure or the like to thereby fix or connect the apparatus to the structure or the like.
In order to ensure that the apparatus is inserted to the correct depth in the hole in the structure or the like, some embodiments of the present invention may include a flange or outwardly extending abutment member on the proximal end of the hollow elongate member to ensure that the proximal end of the hollow elongate member lies flush with the outer surface of the structure of the like.
In a preferred embodiment of this aspect of the present invention, the inner member is provided with one or more grooves in an outer surface thereof. Such grooves are suitably generally transverse grooves. The pins are placed in the grooves and pivotally connected at or near one end to the inner member. The other end of each pin may extend slightly beyond the surface of the inner member. In order to move the pins to the extended position, the inner member may be rotated or turned when the free ends of the pins are in alignment with the holes in the side wall of the hollow elongate member. The free ends of the pins will extend through the holes. As rotation of the inner member continues, the distance between the pivotally mounted ends of the pins and the holes in the hollow elongate member decreases and this causes the pins to move outwardly through the holes until they are fully extended.
In order to enable the inner member to be rotated with the force required to extend the pins into the material of the structure or the like, the proximal end of the inner member may be provided with an engaging surface for engaging with a handle or torque applying means. The torque applying means may be a spanner, wrench, screwdriver, pliers or the like.
The apparatus of the present invention may be fixed or connected to the structure or the like to enable other devices to be fixed thereto. For example, the inner member may be provided with an internal thread to enable another screw or bolt to be joined thereto.
Alternatively, the inner member may extend out of the hollow elongate member (and extend outwardly from the outer wall or surface of the structure or the like when the apparatus is fixed or connected) and the outwardly extending part of the inner member could be used to join or connect other elements thereto.
The apparatus of the present invention could also be used as a fixation device for connecting two structures or the like, such as planks, beams, or bricks together. In this case, holes would have to be made in both of the articles to be connected.